The function of pin coupling to cushion and absorb vibration

Due to the elastic element of the pin coupling, the elastic element can produce greater elastic deformation and damping. Therefore, the pin coupling can not only compensate for the relative displacement of the two shafts, but also cause buffering and vibration absorption.

In the process of mechanical transmission, the load transmitted by the transmission shaft system often changes. The reasons for the load change are different, such as unstable motor speed, unstable load of the working machine, and centrifugal force caused by unbalanced rotating parts in the shaft system. Dynamic loads may cause changes in load.Load changes are often reflected in periodic loads, impact loads and irregularly changing loads. The pin coupling can adapt to load fluctuations and has the ability to buffer and dampen vibration, which is mainly related to the stiffness and damping of the pin coupling. related.

The stiffness of the coupling includes radial stiffness, axial stiffness and torsional stiffness.In actual engineering, load changes are often caused by torsional vibration caused by torque fluctuations, so the main stiffness of the coupling is the torsional stiffness.Under normal circumstances, in shafting transmission, the stiffness of other parts of the system will be much larger than the stiffness of the pin coupling. Therefore, in the simplified case, assuming that the elasticity of other parts is zero, only the coupling is considered. The flexibility of the device.The torsional stiffness of the coupling is used as the torsional stiffness of the drive shaft system.

Although pin couplings generally have buffering and vibration absorption functions, a pin coupling with a certain value of stiffness does not have the effect of damping vibration under the action of any variable torque. Sometimes it will cause strong vibration.Therefore, only when the stiffness of the coupling is coordinated with other parameters and loads of the entire drive shaft system can the effect of vibration reduction be produced.For a certain drive shaft system, the moment of inertia and natural frequency can be obtained. If you know the changing law of the transmitted torque, such as amplitude and frequency, you can establish the differential equation of the shaft system in torsional vibration and solve the equation , You can get the required coupling stiffness.In order to solve the differential equation of motion, it is necessary to simplify the mechanical model of the moment of inertia and stiffness on the driving and driven sides of the coupling in the transmission shaft system.Usually it is more typical to simplify into two equivalent discs, which are arranged on both sides of the coupling.During the work of the coupling, the cyclic load is a typical load form in mechanical transmission.In order to avoid resonance, the changing frequency of the periodic load and the natural frequency of the drive shaft should be staggered.The method is to change the change frequency of the periodic load or change the change frequency of the shaft system.Because the change frequency of the load is related to the speed of the spindle, and the speed is a mechanical performance parameter, generally it cannot be changed at will.Therefore, the purpose of avoiding resonance is generally achieved by changing the natural frequency of the shafting system, and changing the natural frequency of the shafting system generally changes the moment of inertia or stiffness of the shafting system. The moment of inertia is related to the mechanical structure, and it is difficult to achieve by changing the moment of inertia. , And the stiffness of the shaft system is easy to change.Therefore, changing the star-shaped pin coupling is to change the stiffness of the shaft system to achieve the purpose of avoiding resonance.

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